The so-called Mercury Card Fold into fourths, which is executed underneath the deck with both hands, gets its name for its appearance in the effect “Mercury's Card” in Jean Hugard and Fred Braue's Expert Card Technique, 1940, p. 303. However, it had been described four years earlier by Frank Chapman in Six Bits, 1936, in a card to matchbox effect called “A Sure Bet”. Chapman writes that he does not know the originator of the effect and he does not claim the folding technique, which is also uncredited in Expert Card Technique. However, in The Fred Braue Notebooks, Volume 3, 1985, p. 3, Braue credits the move to John Scarne.
A one-handed method for folding a card into fourths is described by William H. McCaffrey in his “Cash and Change-Purse” in The Sphinx, Vol. 37 No. 5, July 1938, p. 113. The same technique is also briefly described in “A Card Mouthful”, “a favorite with John Scarne”, in John Northern Hilliard's Greater Magic, 1938, p. 308.
A one-handed method for folding a card into sixths from classic palm position is also described in Expert Card Technique, 1940, p. 305, as “Folding a Card” with the note that this technique “is preferred by some performers”.